Smart Expense Tracker Android App with Budget Alerts and CSV Export

Students lose track of money in small daily leaks — food delivery, travel, snacks — because existing finance apps are either cloud-dependent, ad-heavy, or too slow to open for a quick entry, so usage dies within a week. Spreadsheets offer no budgets, no alerts and no charts. This project builds a native Android expense tracker designed for daily student use: two-tap expense entry (amount, category, optional note), an offline-first Room database that works in low-connectivity hostels, and a budget engine that warns at 80% of a monthly or category limit and raises a persistent warning at 100%. Spending is visualized on-device with a category donut, a six-month bar trend and per-category progress bars; recurring costs like hostel fees and subscriptions get WorkManager reminders; and the full history exports as clean, spreadsheet-ready CSV. Because the stack is standard Android (Kotlin, Room, WorkManager, MPAndroidChart), the student can explain every layer in the viva — entities, DAOs, reactive UI updates and background jobs.

1. The user taps the + button and enters amount, category and an optional note in the bottom-sheet form; the entry is validated and inserted into the Room database.
2. The repository exposes the transaction table as a Kotlin Flow, so the dashboard totals, donut chart and budget bars refresh reactively on every insert — no manual reloads.
3. The budget engine compares spent totals against the monthly and category limits after each insert, posting a notification at 80% and a persistent home-screen warning at 100%.
4. A WorkManager periodic job runs a daily budget check (catching threshold crossings while the app is closed) and fires due-date reminders for recurring expenses.
5. The Reports screen queries the local database for the six-month trend and renders bar and donut charts with MPAndroidChart, entirely on-device.
6. Tapping Export serializes the transaction table to CSV with proper quoting, then hands the file to the system share sheet so it opens directly in a spreadsheet app.

Tech stack:

• Kotlin, Android SDK (minSdk 24)
• Material 3 components
• Room database (entities, DAOs, migrations)
• Kotlin Coroutines + Flow
• WorkManager (background jobs)
• MPAndroidChart
• CSV export via system file picker
• Git version control

• [Two-tap expense entry] A bottom-sheet form captures amount, one of six categories and an optional note, validates the input, and saves — fast enough to use at a food stall.
• [Offline-first Room database] All transactions, budgets and recurring expenses live in a Room database with entities, DAOs and migration support; the app is fully functional without connectivity.
• [Budget engine with 80%/100% alerts] Monthly and per-category budgets are recomputed on every insert: a notification fires at 80% utilization and a persistent warning appears at 100%.
• [On-device spending charts] Category donut, six-month bar trend and per-category budget progress bars rendered natively with MPAndroidChart — no server, no network.
• [Recurring expense reminders] Hostel fees, subscriptions and recharges are registered once; WorkManager fires battery-safe background reminders on their due dates.
• [One-tap CSV export] The full transaction history serializes to a well-formed, date-ordered CSV (date, title, category, amount) and shares through the system file picker into Excel or Google Sheets.
• [Material 3 interface] Clean, modern Android UI with bottom navigation, cards and the platform's dynamic theming conventions.

• Complete Kotlin source code as an Android Studio project
• Debug APK for direct install and live demonstration
• Demo dataset: one month of realistic student transactions
• Architecture document with entity-relationship and data-flow diagrams
• Project report PDF (background, design, implementation, testing)
• PPT presentation for final review
• Viva Q&A preparation document (Room, Coroutines, WorkManager, charts)